#include "bits/stdc++.h"
#include "combo.h"
/*namespace {
constexpr int MAX_N = 2000;
constexpr int MAX_NUM_MOVES = 8000;
int N;
std::string S;
int num_moves;
void wrong_answer(const char *MSG) {
printf("Wrong Answer: %s\n", MSG);
exit(0);
}
} // namespace
int press(std::string p) {
if (++num_moves > MAX_NUM_MOVES) {
wrong_answer("too many moves");
}
int len = p.length();
if (len > 4 * N) {
wrong_answer("invalid press1");
}
for (int i = 0; i < len; ++i) {
if (p[i] != 'A' && p[i] != 'B' && p[i] != 'X' && p[i] != 'Y') {
wrong_answer("invalid press");
}
}
int coins = 0;
for (int i = 0, j = 0; i < len; ++i) {
if (j < N && S[j] == p[i]) {
++j;
} else if (S[0] == p[i]) {
j = 1;
} else {
j = 0;
}
coins = std::max(coins, j);
}
return coins;
}*/
std::string guess_sequence(int N)
{
std::string p;
for(int i=0;i<N;i++)
{
p += 'X';
}
std::string c = "ABXY";
int cur = 0;
for(int i=0;i<4;i++)
{
p[0] = c[i];
cur = press(p);
if(cur==N)
{
return p;
}
else if(cur==1)
{
break ;
}
}
for(int i=1;i<N;i++)
{
for(int j=0;j<4;j++)
{
if(p[0]==c[j]) continue;
p[i] = c[j];
cur = press(p);
if(cur==N)
{
return p;
}
else if(cur==i+1)
{
break;
}
//else p.pop_back();
}
}
return p;
}
